梭梭土壤种子库空间分布的尺度依赖性研究

Study on Spatial Distribution of Soil Seeds Bank of Haloxylon ammodendron in Gurbantunggut Desert

采用相邻网格法对古尔班通古特沙漠3个梭梭土壤种子库样地（奎屯、五家渠和精河）进行采样,并应用地统计学理论与方法对梭梭土壤种子库空间分布格局的各向异性和尺度依赖性进行了研究。结果表明：（1）梭梭土壤种子库数量为16.05~152.58粒/100m2,奎屯样地种子库变异系数大于五家渠和精河;（2）梭梭土壤种子库空间分布格局强烈,且具有明显的各向异性特征;（3）奎屯和五家渠样地中,随着抽样尺度的加大（5~25m）,土壤种子库空间异质性增强,而精河样地在各个尺度下土壤种子库的空间异质性程度变化不大;（4）空间克里格插值表明,各样地种子密度梯度变化清晰,呈明显聚集分布。地表短命植物层分布决定了梭梭土壤种子库空间分布格局。奎屯和五家渠样地的种子,呈明显的高密度斑块和低密度斑块镶嵌分布格局,精河样地的种子密度低,分布较均匀。

The anisotropy and scale dependency of spatial pattern of soil seed bank of Haloxylon ammodendron were studied using geostatistics,through sampling from the surface to under-ground in three plots by neighboring grid method at Gurbantunggut Desert.The results showed that：（1）The average seed density ranged from 16.05to 152.58seeds/100m2,and the coefficient of variation of seed density in Kuitun plot was higher than in the other two plots.（2）The strong spatial pattern intensities and notable anisotropy were found in soil seed bank.（3）The heterogeneity increased as scale increased from 5mto 25min Kuitun and Wujiaqu plots,while the variation of heterogeneity was slight as scale changed in Jinghe.（4）The kriging map showed that the gradient variations of soil seed bank were significantly,spatial pattern showed remarkable aggregated distribution.The spatial distribution of ephemeral plant determined the spatial distribution of seed bank of Haloxylon ammodendron.The soil seed bank in Kuitun and Wujiaqu plots showed significantly mosaic features between high and low density.The seed density was low and relative homogeneous in Jinghe plot.